2-178566270-G-T

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP6

The NM_001267550.2(TTN):c.79862C>A(p.Thr26621Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000328 in 1,613,500 control chromosomes in the GnomAD database, with no homozygous occurrence. 13/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T26621V) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000035 ( 0 hom. )

Consequence

TTN
NM_001267550.2 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:8B:3

Conservation

PhyloP100: 3.02

Publications

40 publications found

Variant links:

Genes affected

TTN (HGNC:12403): (titin) This gene encodes a large abundant protein of striated muscle. The product of this gene is divided into two regions, a N-terminal I-band and a C-terminal A-band. The I-band, which is the elastic part of the molecule, contains two regions of tandem immunoglobulin domains on either side of a PEVK region that is rich in proline, glutamate, valine and lysine. The A-band, which is thought to act as a protein-ruler, contains a mixture of immunoglobulin and fibronectin repeats, and possesses kinase activity. An N-terminal Z-disc region and a C-terminal M-line region bind to the Z-line and M-line of the sarcomere, respectively, so that a single titin molecule spans half the length of a sarcomere. Titin also contains binding sites for muscle associated proteins so it serves as an adhesion template for the assembly of contractile machinery in muscle cells. It has also been identified as a structural protein for chromosomes. Alternative splicing of this gene results in multiple transcript variants. Considerable variability exists in the I-band, the M-line and the Z-disc regions of titin. Variability in the I-band region contributes to the differences in elasticity of different titin isoforms and, therefore, to the differences in elasticity of different muscle types. Mutations in this gene are associated with familial hypertrophic cardiomyopathy 9, and autoantibodies to titin are produced in patients with the autoimmune disease scleroderma. [provided by RefSeq, Feb 2012]

TTN links:

TTN-AS1 (HGNC:44124): (TTN antisense RNA 1) This gene encodes a non-coding RNA transcribed from the opposite strand to the titin gene. [provided by RefSeq, Aug 2016]

TTN-AS1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -1 ACMG points.

BP6

Variant 2-178566270-G-T is Benign according to our data. Variant chr2-178566270-G-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 192203.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTN	NM_001267550.2 link	c.79862C>A	p.Thr26621Lys	missense_variant	Exon 326 of 363	ENST00000589042.5	NP_001254479.2	A0A0A0MTS7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTN	ENST00000589042.5 link	c.79862C>A	p.Thr26621Lys	missense_variant	Exon 326 of 363	5	NM_001267550.2	ENSP00000467141.1		A0A0A0MTS7

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

151914

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.000478

GnomAD2 exomes

AF:

0.0000442

AC:

AN:

248856

AF XY:

0.0000444

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000203

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000266

Gnomad OTH exome

AF:

0.000165

GnomAD4 exome

AF:

0.0000349

AC:

AN:

1461468

Hom.:

Cov.:

AF XY:

0.0000358

AC XY:

AN XY:

727026

show subpopulations

African (AFR)

AF:

0.0000598

AC:

AN:

33458

American (AMR)

AF:

0.000134

AC:

AN:

44714

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26128

East Asian (EAS)

AF:

0.00

AC:

AN:

39686

South Asian (SAS)

AF:

0.00

AC:

AN:

86250

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53386

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.0000369

AC:

AN:

1111722

Other (OTH)

AF:

0.0000331

AC:

AN:

60358

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.487

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000132

AC:

AN:

152032

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74300

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41478

American (AMR)

AF:

0.00

AC:

AN:

15264

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5130

South Asian (SAS)

AF:

0.00

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10570

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

67978

Other (OTH)

AF:

0.000473

AC:

AN:

2112

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

12303

ExAC

AF:

0.0000165

AC:

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:8Benign:3

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

not specified

Uncertain:1Benign:2

Apr 09, 2025

Molecular Diagnostic Laboratory for Inherited Cardiovascular Disease, Montreal Heart Institute

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jun 24, 2013

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:research

- -

Aug 22, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: TTN c.72158C>A (p.Thr24053Lys) results in a non-conservative amino acid change located in the A-band domain of the encoded protein sequence. Two of three in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 4.4e-05 in 248856 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in TTN causing Limb-Girdle Muscular Dystrophy, Type 2J, allowing no conclusion about variant significance. To our knowledge, no occurrence of c.72158C>A in individuals affected with Limb-Girdle Muscular Dystrophy, Type 2J and no experimental evidence demonstrating its impact on protein function have been reported. ClinVar contains an entry for this variant (Variation ID: 192203). Based on the evidence outlined above, the variant was classified as uncertain significance. -

not provided

Uncertain:1Benign:1

Oct 14, 2020

Revvity Omics, Revvity

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Nov 16, 2020

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Autosomal recessive limb-girdle muscular dystrophy type 2J

Uncertain:1

Apr 28, 2017

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

Autosomal recessive limb-girdle muscular dystrophy type 2J;C1858763:Dilated cardiomyopathy 1G

Uncertain:1

Dec 28, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Dilated cardiomyopathy 1G

Uncertain:1

Apr 28, 2017

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Early-onset myopathy with fatal cardiomyopathy

Uncertain:1

Apr 28, 2017

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Tibial muscular dystrophy

Uncertain:1

Apr 28, 2017

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Myopathy, myofibrillar, 9, with early respiratory failure

Uncertain:1

Apr 28, 2017

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.20

BayesDel_addAF

Benign

-0.22

BayesDel_noAF

Benign

-0.28

CADD

Benign

(source)

DANN

Benign

0.85

Eigen

Uncertain

0.24

Eigen_PC

Uncertain

0.33

FATHMM_MKL

Uncertain

0.93

LIST_S2

Uncertain

0.96

D;D;D;.;D;D;D

M_CAP

Benign

0.041

MetaRNN

Uncertain

0.44

T;T;T;T;T;T;T

MetaSVM

Uncertain

-0.28

MutationAssessor

Benign

0.97

.;.;.;L;.;.;L

PhyloP100

3.0

PrimateAI

Uncertain

0.52

PROVEAN

Uncertain

-3.7

D;D;.;.;D;D;.

REVEL

Benign

0.22

Sift

Benign

0.048

D;T;.;.;T;D;.

Polyphen

0.58

.;.;.;P;.;.;P

Vest4

0.39

MutPred

0.56

.;.;.;Gain of methylation at T24980 (P = 0.0105);.;.;Gain of methylation at T24980 (P = 0.0105);

MVP

0.38

MPC

0.22

ClinPred

0.095

GERP RS

5.0

Mutation Taster

=90/10

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over